The CT-199 was specified for many uses as the data sheet shows. The bias and anove voltage for various uses are given. The base is American on this exhibit, for the UK market it was also made with a B4 base. Our other CT-199 came in a box that was marked British base but it too has an American base, in that case the UV bayonet base.
The short base pins and locating pip on the base indicate a bayonet type base. The size is intermediate between the peanut of the Wecovalve and the first standard American base the UV.
There is a small window in the gettering and the vertical anode cylinder can be seen within.
The grid seems close to the anode with the filament held at the bottom of the valve.
The wide glass tube envelope is 25 mm in diameter, and excluding the base pins is 85 mm tall.
References: Datasheet & 1043. Type CT-199 was first introduced in 1925.